Quote Originally Posted by Enkidoh View Post
Considering only FFVIII featured him as a summon spell - the rest of his canon appearances have been as a hidden antagonist/optional boss battle outside the main story, I doubt very much he'll be made a pseudo-Primal-egi for SMN, sorry. He's actually part of the Hildibrand quest line and will feature in it until it's resolution, and then that would be it.

And FFV clearly explained how Gil ended up in FFVIII's world - when Seifer destroyed Odin Zantesuken ruptured the 'dimensional interval' to the Void where he had been trapped since the end of FFV, thus freeing him. Hence why in FFVIII he just simply came and went - he wasn't a summon truly but more just a wandering fighter looking for worthy opponents.
I could be wrong but I don't think he ever obtained Excalibur in FFV. So, how had he already obtained it in FFVIII then?